Incandescent lamp



April 7, 1942. A. DE CASTRO V INCANDESCENT LAMP File d Oct. 51, 1940- v IN VEN TOR.

"14' 1-1 lIIIIlIIIllIIII/A nected as indicated in Fig. 1.

Patented Apr. 7, 1942 UNITED STATES PATENT OFFICE INCANDESCENT LAD [P Adolphe de Castro, Los Angeles, Calif. duplication October 31, 1940, Serial No. 363,622

2 Claims.

This invention relates to incandescent electric lamps of the kind having two or more filaments and has particular reference to the positioning ing black through use.

A further object is to secure for a spare or .unused filament a higher degree of luminosity when it becomes automatically incandescent.

Still other objects will become apparent as the specification proceeds.

In the drawing:

Fig. "1 is a combination of a side elevation of a filament control device and a diagram of the wiring circuit of the'lamp. I

Fig. 2 is a'per'spective View of the control device shown in Fig. 1.

Fig. 3 is a front elevationof one form of the lamp,'showing one arrangement of the filaments and indicating the filament control device in the base.

Fig, 4 is a top plan view of in Fig. 3.

Fig. 5 is aside elevation of the bulb and filament arrangement shown'in Figs. 3 and 4, with a bayonet or pre-focus base substituted for the threaded type shown 'in Fig. 3.

Fig. Gis a top plan view of a modified filament arrangement.

The invention herein described, although usethe lamp shown ful in many classes of multi-filament lamps, is"

thermostat element 2, and is connected to lead 1 which is joined at its other end to filament 8. When the thermostat element 2 is cool, the contact point 9, on the free 'end of the element,

rests on contact point I0 fixed to the wafer 5 v .and electrically connected by means of wire II to filament l2.- The other end of filaments 8 and I2 are both connected to the common return conductor l3. Conductor I is connected to the usual terminal H3 in the bottom of the base B of the lamp, as indicated in Fig. 3, and conductor I3 is connected to the base at l5.

When current is initially introduced through these wires, it will be obvious that filaments 8 and I2 are connected in parallel, the current to i heatsthermostat element 2, causing it torise stat drops ina few seconds and closes the cirparticular-1y adaptable to the types disclosed in my Patents No. 1,758,434 and No. 1,538,372, and

the invention will therefore embodiments.

In lamps of the latter class, a plurality of filaments-are provided together with means where-, by' only one filament remains incandescent at a time, the burning out or rupturing of one fila- .ment acting to switch another filament into the circuit. In one such embodiment of. my inventi'on, two filaments and a control device are. con- 7 The conductor I is electrically connected to the fixed end of the thermostat element 2 and to the fixed end of resistance wire 3 by a rivet I or other suit- Y able means passing through the wafer of nonconducting-material 5 The resistance wire 3 is from its rest position, lifting contact 9 from contact I0, thus breaking the circuit to filament l2. As the thermostat increases'in temperature, it will continue to rise until it strikes the lim iting stop [4.

When the' current is turned oil, the cooling thermostat element will gradually move toward its rest position where it will again close the circuit to filament 12. When filament 8 finally burns out,'or in the event of its rupture or breakage, the circuit through the heating coil is of course broken, with the result that the thermocuit through filament l2. As current never again passes through ,the heating coil, contacts 9 and in now remain'permanently closed. The limiting stop l4 serves to reduce the interval of time required for the second filament l2 to replace filament 8 as the illuminating means, as it limits the throw of the thermostat and thus reduces the arc through which it must travel until it closes the ciicuit to the spare filament.'

Byfollowing the teachings of my Patent No.

' 1,758,434, the heating .coil may be omitted if it conducts to open'the contacts 9 and I 0..

The present invention contemplates special filament arrangements for atwo-fold purpose. The first of these has to do with a method of preventing thev well-known blackening of the bulb from-the continuous effect of the filament emissions, and the second is concerned with meansv whereby the two filaments have substantially the same optical centers. These two ends 2 w b may both be served, by'arrangements typified by those disclosed in the drawing.

In Fig. 4, both filaments are shown to have a coiled or sigmoidal form, and each is arranged in the general shape of the letter c.- One filament is placed inside the c formed by the other, as indicated in Fig. 4, and both are disposed in substantially the same plane, as shown in Fig. 3. If these filaments are of the same thickness, it is necessary that they be of approximately the same total length in order properly to operate on the same voltag and the convolutions or bulb happens to be oriented.

wavesof the inner filament must therefore be either closer together or kinked into longer folds than the outside filament. The mid-sections of the filaments are supported-on arms ll embeddedinthesupportingcoresEandqandthe ends are supported by conductors to and lb, and

lid and Rh, each pair leading respectively tofilaments 8 and I2.

Fig. 6 shows another suitable filament configuration to accomplish the purposes hereinbefore set forth. As in Fig. 4, both filaments have a c or crescent formation, but instead or one being placed totally within the arc of the other, they may have configurations of identical shape and size, but the openings in the crescents face in opposite directions and one end of each crescent is positioned inside the other. As in the configurations shown in Figs. 3 and 4, both filaments are disposed in substantially the same plane. The filament supporting structure will be obvious from an examination of Fig. 6.

possible within the spare filament will exhibit a coating not found on the first. the relatively fresh condition of the filament, but rather to a collection or gathering of small particles emitted fromthe incandescent filament. These emanations, passing from the luminous to the dark filament, are indicated at F in Fig. 4. When there is not a second element in proximity to the incandescent filament, these emanations rise and darken whatever portion of the bulb is on top inthe particular position in which the Asecond filament,

arranged in the bulb according to the teachings of this specification, gathers these minute particles thrown off from the incandescent filament, thus preventing the discoloration of the bulb. The coating thus acquired by the second filament also acts to produce -a higher illumination when it finally comes into use than would otherwise be the case.

'Many other suitable filament -rrangements are the broad scope of this invention, and it will be obvious to the art that my invention may be embodied in sundry other forms, and that various substitutions may be made for the individual elements set forth in the claims without departing from In the filament arrangement shown in Figs. 3

and 4, the two filaments are physically substantially concentric, and they are therefore substantially concentric from an optical standpoint. This is true in any position of the lamp, as will be evident from an examination of Figs. 3, 4

and 5. In Fig. 6, there is a slight displacement of the optical centers, but for most practical purposes the variation is negligible.

If a lamp of this type is examined before either filament has burned out, but after the first filament'has been in use for a few hundred hours,

filaments each having the general the combinations covered thereby.

- My claims are:

1. An incandescent lamp including-a pair of configuration of an incomplete circle, the open portions of the two configurations facing '.in substantially opposite directions with an end portion of one filament within the circle of the other; and a'common conductor leading to each of said filaments.

2. An incandescent lamp including a pair of coiled filaments of many convolutions, each fila-' ment having a generally O-sh'aped configuration;

one of said filaments disposed within the c formed by the other filament and having its convolutions so formed that the actual filament length is substantially the same as that of the.

outer filament; and a. common conductor leading to one terminal of each of said filaments.

' ADOLPHE n: CASTRO.

This coating is'not due to those'skilled in.- 

